Örjan Sandred - Composer
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(CAC cont.)

strategy for how to find an acceptable solution. After having struggled with some of the existing constraint solving systems, it became necessary for me to develop a new, more efficient constraint solver that could handle more complex musical formalizations. I needed a system that could approach the problem from an angle where the nature of a music structure is taken into account.

The constraint solving systems I have been developing as part of my research use several search engines that work in parallel. The order of how decisions are made by the system becomes more flexible, and also more efficient. One of the challenges has been how to guide the system during the search process: When several engines work semi-independent, it is a risk that the system misses to try some combinations of the elements. It is also a risk that the system re-tries combinations it already dismissed. Another challenge has been to solve how the system should backtrack when it needs to reconsider previous decisions in order to satisfy the given constraints.

The outcome of my ongoing technical development is the Cluster Engine. It is now at a stage where I have been able to use the system in my creative work as a composer. Compared to my own earlier work, the Cluster Engine has proven to outperform my previous constraint solving systems by far.


The objective of my research is to create my own music. An early example of using OMRC in a composition is Amanzule Voices for cello and live electronics. In this piece all rhythms where put together using the OMRC library. Since OMRC does not handle pitch, these where composed on top of the generated rhythm score.

Whirl of Leaves for flute and harp was composed using the PWMC library. Melodic phrases, rhythms, harmonic progression, definitions of consonants and passing notes and relationship between the two voices are all controlled by the PWMC system. Even though it was not primary my purpose to strictly follow the computer's suggestions, the score of Whirl of Leaves is very close to the structure that the system generated. My main work with this composition was to understand and find relationships between parameters in the score.

Flames and Blazes for recorder, trombone and cello was composed using the Cluster Engine. The system made it possible to formalize a nested web of relationships within the musical score.

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